AFO question?

I have a question about AFO’s that I heard Julie talk about! I know it has something to do with helping a person walk better. Is it a certain kind of leg brace? Not really sure what AFO’s are and what they are for?
Reason asking is my mother has a neuropathy problem in her legs but has arthritis really bad also in her knees. She had knee replacement in one leg several years ago but had a really bad time with that surgery. She was in her early 60’s when she got the replacement and her health is not all that great.
Now she is 73 with other health issues like neuropathy and a few other things.
Her other knee now is getting ready to blow out on her and I have a bad feeling about this. Plus the replacement in the other knee is almost due for a new one because it’s been over due and might be acting up too. Yesterday while my husband an I were there she was complaining about the grinding pain in her knee. And was having a horrible time walking with that leg.
I have one big fear for her! If we get a knee replacement done with that neuropathy problem. Will she be strong enough to be able to get back on her feet after that surgery. Plus with her health and age I fear that too! It took my mother 6 months on that last surgery she had when she was in her early 60’s. 6 months my father had to care for her.
Here I have a problem with my health right now and really serious situation too and my mom needs attention herself medically. But what if the surgery is to risky and doctors say no! What can the AFO do for her! Are they comfortable wearing or hard to wear? Any input would be helpful. The more I find out then maybe I can get something like this done for her. My mom is going to end up in a wheel chair. I have been seeing it. She refuses to except that though and is not giving up on walking just yet. But may have no choice. This might be an option for her though! Especially with the neuropathy problem also.
Thanks for any advice!